Frozen water in pipes can cause water pressure buildup between the ice blockage and the closed faucet at the end of a pipe, which leads to pipes bursting at their weakest point. Pipes in attics, crawl spaces and outside walls are particularly vulnerable to freezing in extremely cold weather, where holes in your house's outside wall for television, cable or telephone lines allow cold air to reach them. To keep water in pipes from freezing, take the following steps: • Fit exposed pipes with 2" fiberglass insulation sleeves or wrapping to slow the heat transfer. The more insulation the better.

• Seal cracks and holes in outside walls and foundations near water pipes with caulking. It's especially important to keep cold wind away from pipes, which speeds up the freezing process.

• Keep cabinet doors open during cold spells to allow warm air to circulate around pipes (particularly in the kitchen and bathroom).

• Keep a slow trickle of water flowing through faucets connected to pipes that run through an unheated or unprotected space. Ice might still form in the pipes, but an open faucet allows water to escape before the pressure builds to where a pipe can burst. If the dripping stops, it may mean that ice is blocking the pipe; keep the faucet open, since the pipe still needs pressure relief. Or drain the water system, especially if your house will be unattended during cold periods.

• Pipes in attics and crawl spaces should be protected with insulation or heat. Pipe insulation is available in fiberglass or foam sleeves. Home centers and hardware stores have sleeves providing 1/8 to 5/8 inches of insulation; specialty dealers have products that provide up to 2 inches of insulation. The extra thickness is worth the price and can save a pipe that would freeze with less insulation.

• Heating cables and tapes are effective in freeze protection. Select a heating cable with the UL label and a built-in thermostat that turns the heat on when needed (without a thermostat, the cable has to be plugged in each time and might be forgotten). Follow the manufacturer's instructions closely.

If You Suspect a Frozen Pipe:

If you open a faucet and no water comes out, don't take any chances. Call a plumber. If a water pipe bursts, turn off the water at the main shut-off valve (usually at the water meter or where the main line enters the house); leave the faucet(s) open until repairs are completed. Don't try to thaw a frozen pipe with an open flame; as this will damage the pipe and may even start a building fire. You might be able to thaw a pipe with a hand-held hair dryer. Slowly apply heat, starting close to the faucet end of the pipe, with the faucet open. Work toward the coldest section. Don't use electrical appliances while standing in water; you could get electrocuted.

Sprinkler Systems:Drain the water from the pipes and then turn your automatic sprinkler system off. This will prevent your pipes from bursting and also prevent ice accumulation on sidewalks, driveways and roadways